Many types of sports footwear, including mountain boots and in particular ski boots or snowboard boots, consist of an upper part or casing, open at the upper part to allow the foot to be inserted, associated with a sole. The sole is normally provided, in its lower part, with notches where water can drain out, and shaped protrusions at the tip and in the heel so the bindings, respectively front and rear, of the ski can be attached.
Solutions are also known where the sole comprises an insole with which an anti-slip support element is associated, made in either one piece or as a number of pieces, and having a thickness adequate to guarantee the right consistency and heat protection to the boot.
An example of how to guarantee the attachment of the anti-slip support element and the insole is described and claimed in the American U.S. Pat. No. 3,273,263.
In any case, the anti-slip support element generally has, on its bottom surface, shapings given by the alternation of ridges and grooves, in order to guarantee that the boot has a good grip on the ground, especially for walking on snow, ice-covered or uneven ground and/or steep slopes, either up or down.
The greater the difference in height between the ridges and grooves, the better the boot grips the ground.
Furthermore, the anti-slip support element is normally made of a rather soft material so as to intensify its grip on the ground.
It is also known that bindings for ski boots are adjusted depending on the overall thickness of the sole. If the sole is subject to deformations or localized compression, as a consequence of stresses of various type applied to it during use, the stability of the ski boot inside the binding is reduced.
One disadvantage of normal ski boots is that, when they are used in combination with skis, the anti-slip support element tends to deform as it is subjected to tension exerted by the ski bindings. Added to this tension there are also the stresses exerted by the skier on the boot, especially going around bends, when the skier's weight is put more on the edges of the skis.
The deformation is a consequence of the softness of the material of which the anti-slip support element is made, and of its shaping, having alternate ridges and grooves.
The deformation of the anti-slip support element causes a reduction in stability of the boot inside the bindings of the ski, with a consequent reduction of safety for the skier.
A further disadvantage linked to the deformation of the anti-slip support element is that this absorbs part of the force exerted by the skier, which otherwise would be discharged onto the binding and consequently on the ski. This reduces the skier's perception of having optimal control of his skis.
In order to reduce these disadvantages, the most used solution is to make a more rigid sole and with a much reduced difference in height between ridges and grooves. This however reduces the grip between the anti-slip support element and the ground, when the boot is used for walking.
Another solution adopted is to adjust the bindings so that they press with greater force on the portions of the sole of the boot with which they are in contact, with the result, however, that it is more difficult to insert such portions of sole into the respective bindings, yet without completely solving the problem when the anti-slip support element is deformed and compressed during skiing.
One purpose of the present invention is to increase the stability of the attachment of the skis and boots, that is to say, to reduce the movement of the boot inside the binding when the boot is used for skiing, at the same time maintaining good gripping capacity of the sole of the boots when these are used for walking.
A further purpose is to reduce the number of accidents due to a perceived instability of the boot inside the binding of the skis, and at the same time to guarantee a safe walk on uneven or snow-covered ground when the boots are used without the skis.
A further purpose of the present invention is to guarantee that the boot enters easily into the binding.
Another purpose is to enable the skier to discharge the weight force applied on the bindings, and therefore on the skis, and to prevent part of said force from being absorbed by the deformation of the sole.
The Applicant has devised, tested and embodied the present invention to overcome the shortcomings of the state of the art and to obtain these and other purposes and advantages.